Introduction to Geophysics

Summary

This course presents a broad overview of geophysical topics and techniques, including magnetism, heat flow, gravity and both active and passive source seismology. An underlying theme for the course is the evaluation of geological phenomena such as plate tectonics or mantle plumes, using multiple geophysical techniques.

Course Context:

This is an upper division course, required for all students earning a B.S. in geology. Prerequisites are introductory geology, structural geology, introductory physics and differential calculus.

Course Goals:

Students should be able to synthesize data collected using different geophysical methods and apply them to a single process.

Students should be able to translate mathematical concepts into descriptive statements, explaining the processes represented by equations.

Students should be able to interpret geophysical data, including seismic reflection profiles, earthquake focal mechanisms, and gravity anomalies.

Students should be able to derive and evaluate equations describing geophysical processes.

Students should be able to apply quantitive methods in support of geological analyses.

How course activities and course structure help students achieve these goals:

The body of the course is focused on introducing concepts of geophysics, with plate tectonics serving as the framework for each method. Thus, discussions of seismology may center on using focal mechanisms to examine stresses within plate boundaries, and quantifying past plate motions is a major goal of the magnetism section. Students thereby learn to apply geophysical techniques a larger process. The class is fairly quantitative, but all equations are introduced in both mathematical and descriptive formats, to emphasize the fact that equations are simple descriptions of physical processes. To promote this more qualitative approach to math, students keep an "equation dictionary" in which they write descriptive summaries of each equation. As a final project, students break into small groups, each of which investigates one geophysical technique (gravity, heat flow, etc) as it has been applied to the study of hot spots and mantle plumes. Following group presentations, the class debates our current understanding of the topic through analysis of the geophysics and discussion of the scientific process.

Skills Goals

Students taking this course gain significant skills in terms of quantitative analyses. Students also gain experience in the use of MATLAB software.

How course activities and course structure help students achieve these goals:

Assignments in the class are largely quantitative, relying on manipulation and derivation of equations and concepts of physics. Students do weekly problem sets, each of which involves at least one problem that is to be solved using MATLAB software.

Attitudinal Goals

A major goal of this course is to improve student confidence in their quantitative skills.

How course activities and course structure help students achieve these goals:

The primary goal of the equation dictionary project is to show students that they can express mathematical relationships in two ways: through equations and through descriptive summaries of these relationships. If students can look at an equation and "translate" it into a prose sentence, it can help alleviate their fear of mathematical symbols. Some homework assignments include short essay questions that require students to describe physical relationships. For example, students are given a figure showing P-wave velocity, S-wave velocity and density through the Earth. Based on this plot and their knowledge of the equations for P and S wave velocities, students are asked to write an essay describing how bulk and shear moduli change with depth in the Earth.

Assessment

Students do weekly problem sets, each of which comprises 4-5 questions requiring them to manipulate equations presented in class. There are four exams (3 mid-terms and a final). The style of exam questions is similar to those presented in problem sets, but they tend to be more comprehensive...students are asked to synthesize several concepts in addressing a topic, or apply several geophysical techniques to a single problem. Some homeworks or exams include short essay questions, such as explaining the limitations of different magnitude scales in seismology or examining isostatic compensation on other planets. Students are also evaluated on their equation dictionaries and their group presentations of the geophysics associated with hot spots and mantle plumes.

Provenance: Sean Fox, Carleton CollegeReuse: This item is offered under a Creative Commons Attribution-NonCommercial-ShareAlike license http://creativecommons.org/licenses/by-nc-sa/3.0/ You may reuse this item for non-commercial purposes as long as you provide attribution and offer any derivative works under a similar license.

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